This invention relates to a track broom bristle for use on a broom machine adapted for maintenance work on a railway road bed.
Such broom machines are used for dressing the surface of ballast of the bed between and along the sides of the rails, generally termed the ballast bed, and for leveling and distributing ballast over the bed. Such broom machine employs a plurality of broom bristle elements in combination with a rotating drum and element support for use on a broom machine.
Railway ballast generally comprises a thick layer of crushed limestone or similar material resting on a prepared base, in which track cross ties are embedded and supported. The ballast bed is shaped to have a generally horizontal top face over the length of the ties, that is, between the rails and alongside the rails and to have sloped banks at and beyond the ends of the ties. Desirably, the top surface of the ballast is level with or slightly below the top faces of the ties, and the ties and rails should be free of loose ballast and other debris.
Both in maintenance and original construction of the road bed, new ballast is dumped onto the road bed from rail cars and is roughly distributed by a blade device, such as a plow or mold board. However, it is not possible for such a blade device to produce the desired finished condition in which the ballast is level with or slightly below the tops of the ties. A broom machine with a sweeper bristle element can produce the desired distribution of the ballast. The sweeping of ballast, however, imposes a severe load on a sweeper bristle element so that such elements are subject to heavy wear and generally a short life.
Various types of bristle elements have been previously used, for example, such as bristle elements constructed of links of steel cable encased in rubber are removably fastened to a mandrel or drum of the broom machine. The rubber cover is used to control fraying of the cable. With such a bristle element it was found that in ballast dressing operations, such steel cable bristles would last only for a short period of time before requiring replacement. Further, such bristles require significant replacement time.
In other instances, a bristle element is replaceably mounted on a mandrel rotatable on a horizontal axis. These bristle elements have cores made of a bundle of parallel straight steel splines or wires fixed together at one end in a detachable coupling and encased in a resilient sheath which binds the splines into mutually supporting relation and distributes flexing stress in them away from their fixed end. Such a combination is complex to manufacture and expensive to assemble because of the many and various components and the machining necessary to create the structure.
The present invention is directed to a bristle element that is easier and more economical to manufacture and relatively easy to assemble wherein the bristle has suitable wear life and can be easily mounted on a rotating drum.